Flow control in the C shell
The shell contains commands that can be used to regulate the flow of control in command files (shell scripts) and (in limited but useful ways) from shell command-line input. These commands all operate by forcing the shell to repeat, or skip, in its input.
The foreach, switch, and while statements, and the if-then-else form of the if statement, require that the major keywords appear in a single simple command on an input line.
If the shell input is not searchable, the shell buffers input whenever a loop is being read and searches the internal buffer to do the re-reading implied by the loop. To the extent that this is allowed, backward gotos succeed on inputs that you cannot search.